My ACER 5520 laptop starts booting, screen all black - I ear fan, then lights of hdd light up... and nothing happens, the fan shuts down and the laptop reboots again for several times in a row, eventually it manages to show the welcome screen and proceeds to start windows normally.
This is bugging me - I had the same issue with another laptop in the past and since I work from home, just bought a new one.
2 possible problems can cause this:
1) you possibly have a tdss4 boot block rootkit it can cause issues like this to check for one google tdsskiller download to desktop and run.
2) Hard drive failure you may have either crosslinked files or bad sectors
to check for crosslinked files open computer right click on properties of your hard drive c:
tools tab and click on error checking-click check now and set for boot time scan -restart windows
if you have bad sectors it will show up at the end of scan.